Transition metal compounds

ABSTRACT

BRIDGED DINUCLEAR TRANSITION METAL COMPOUNDS ARE PREPARED BY THE REACTION OF A FIRST TRANSITION METAL COMPOUND HAVING TWO NON-CHELATING LIGANDS CONTAINING ELECTRONDONATIONG GROUPS, IN CIS POSITIONS RELATIVE TO EACH OTHER, WITH A SECOND TRANSITION METAL COMPOUND CONTAINING TWO DISPLACEABLE LIGANDS ALSO IN CIS POSITIONS RELATIVE TO EACH OTHER, SO THA A BRIDGED DINUCLEAR PRODUCT IS FORMED WITH THE ELIMINATION OF THE DISPLACEABLE LIGANDS.

United States Patent US. Cl. 260429 R 4 Claims ABSTRACT OF THE DISCLOSURE Bridged dinuclear transition metal compounds are prepared by the reaction of a first transition metal compound having two non-chelating ligands containing electrondonating groups, in cis positions relative to each other, with a second transition metal compound containing two displaceable ligands also in cis positions relative to each other, so that a bridged dinuclear product is formed with the elimination of the displaceable ligands.

This invention relates to a process for preparing bridged dinuclear transition metal compounds, in which the metal atoms may be the same or difierent.

According to the present invention a first transition metal compound having two non-chelating ligands containing electron-donating groups in cis positions relative to each other, is reacted with a second transition metal compound containing two displaceable ligands also in cis positions relative to each other, so that a bridged dinuclear product is formed with elimination of the displaceable ligands.

The transition metals of Groups IV-A to VIII and I-B of the Periodic Table may be incorporated in compounds produced by the process of our invention. Examples of suitable transition metals include titanium, molybdenum, cobalt, rhodium and ruthenium, platinum, palladium and nickel.

The term displaceable ligand refers to any ligand bonded to the second transition metal compound which is displaced in the course of the reaction by the electrondonating atoms of the ligands of the first transition metal compound. Typically these are neutral ligands such as hydrocarbon ligands like norbornadiene or ethylene. Phenyl cyanide is also readily displaceable. Alternatively they may be co-ordinated solvent molecules, such as ethers, for example 2-methoxyethanol. It should be noted that a single ligand of the norbornadiene type leaves the second transition metal compound to form both of the necessary co-ordination sites.

The term electron-donating group is used to include groups comprising atoms of elements of Groups V-B, VIB and VII-B of the Periodic Table of Elements, especially, sulphur, the halides, and unsaturated hydrocarbon groups, such as acetylenic groups. The process of the invention is exemplified formally by the following general equation, which has no steric significance other than illustrating the cis relationship of the reacting ligands ice (U M )p X I... In the above equation M and M represent transition metal atoms, which may be the same or difierent. The first transition metal compound containing metal M also contains two non-chelating ligands X-Rn (wherein X represents an electron donor atom, R represents substituents and n is an integer, being 2 when X is a Group V-B element, 1 when X is a group VI-B elements and 0 when X is a Group VII-B element). It also contains mother ligands L which satisfy the co-ordination requirements of metal M. The second transition metal compound contains displaceable ligands L, (or a single divalent ligand such as norbornadiene) and p further ligands L. In the course of the reaction, ligands L are displaced to give a single bridged compound as the product.

The process is conveniently carried out in a solvent which may be inert or capable of liganding with the second transition metal compound to form displaceable ligands. Examples of suitable solvents are toluene, methylene chloride or Z-methoxyethanol. The reaction usually occurs at room temperature and pressure though higher or lower temperatures and pressures may be used if desired. The product often precipitates out of solution, though recovery may be aided by evaporation of the solvent and/or addition of a precipitating agent such as an aliphatic hydrocarbon. The products may be purified by recrystallisation or by chromatography. Since the starting materials and products are often air and water sensitive, reaction should be carried out under dry, inert atmosphere, for example, nitrogen.

The products of the process of my invention are useful as catalysts in a wide range of organic reactions. For example, compounds containing ruthenium may be used as hydrogenation catalysts; compounds containing platinum may be used as hydrosilation catalysts.

The invention will now be illustrated by the following examples in which parts are by weight.

All reactions were carried out under nitrogen.

EXAMPLE 1 Dicyclopentadienyldithiophenyltitanium (20 parts) and norbornadienetetracarbonylmolybdenum (15 parts) were dissolved together in toluene (430' parts) and the solution was stirred for 24 hours at room temperature. The purple colour of the starting material was retained but a deep blue solid was deposited. This compound is soluble in methylene chloride (from which it is reprecipitated by methylcyclohexane), chloroform, tetrahydrofuran, acetone and sparingly so in benzene. It does not decompose below 230 C. The infrared spectrum shows the presence of cyclopentadienyl, thiophenyl and carbonyl functions.

Elemental analysis.-(Calculated figures in brackets), percent: C, 51.1 (51.6); H, 3.2 (3.3); S, 11.2 (10.6).

Analytical data is consistent with the structure:

where cpd cyclopentadienyl and Ph=phenyl.

3 EXAMPLE 2 EXAMPLE 3 Bis(ethylene) rhodium (I) acetylacetonate (10 parts) was dissolved in toluene (350 parts) and bis(triphenylphosphine) nickel dichloride (24 parts) was added. After stirring for 2 hours at room temperature, a yellow pre cipitate (321 parts) was filtered off, washed with pentane and dried. Melting point: 140142 C.

Elemental analysis.C, 57.8 (57.3); H, 4.8 (4.4); Cl, 7.3 (8.2).

Analytical data is consistent with the structure:

Rh (acac) EXAMPLE 4 Bis(phenyl cyanide) palladium dichloride (10 parts) and bis(triphenylphosphine) cobalt dichloride (17 parts were dissolved in methylene chloride (650 parts) and the solution was stirred for 15 hours. A pale yellow powder (28 parts) was precipitated and was filtered off, washed with methylene chloride and dried. Melting point 235- 237 C. with decomposition.

Elemental analysis.-C, 50.1 (52.0); H, 3.7 (3.6); CI, 17.0 (17.5); Pd, 12.8 (12.8); Co, 9.3 (7.0).

Analytical data is consistent with the structure:

H, 3.8 4.4; Ci,

C(PPll3)2 Cl EXAMPLE 5 Bis(phenyl cyanide) platinum dichloride parts) and bis(triphenylphosphine) cobalt dichloride (14 parts) were dissolved in methylene chloride (600 parts). After two hours, a white precipitate (20 parts) formed which was filtered off, washed with methylene chloride and dried. Melting point: 250 C.

Elemental analysis.C, 45.5 (46.0); H, 3.4 (3.2); CI, 14.9 (15.3); Pt, 15.5 (21.0); Co, 5.1 (6.4).

Analytical data is consistent with the structure:

EXAMPLE 6 Bis(phenyl cyanide)palladium dichloride (10 parts) and bis(triphenylphosphine) nickel dichloride parts) were dissolved in methylene chloride (900 parts). A yellow precipitate immediately formed and all trace of the nickel complex disappeared. The mixture was stirred for an hour to complete the reaction and the product (17 parts) was then filtered off and dried. Melting point: 250 C.

Elemental analysis.C, 50.2 (52); H, 3.9 (3.6); Cl, 17.2 (17.0); Pd, 10.5 (13.4); Ni, 7.6 (7.0).

. 4 Analytical data is. consistent withthe structurez N1(PPh3)2 EXAMPLE 7 Bis(pheny1 cyanide) palladium dichloride (10 parts) and dicyclopentadienyldithiophenyltitanium (11 parts) were dissolved in toluene (500 parts) and stirred for an hour, after which a red precipitate formed. After afurther half hour the product (II parts) was filtered oiiand dried. Melting point: 250 C.

Elemental analysis.C, 46.0 (46.2); H, 3.3 (3.5); CI, 10.2 (12.4); Ti, 9.1 (8.5); Pd, 20.2 (18.5).

Analytical data is consistent with the structure:

I Ph

EXAMPLE 8 Bis diphenylphosphino) ethanedithiophenylnickel 18 parts) and bis(ethylene) rhodium acetylacetonate (5 parts) were dissolved in toluene. After two hours a precipitate (13 parts) was filtered off and dried. Melting point: 265 C.

Elemental analysis.C, 59.3 (58.9); H, 4.2 (4.9).

Analytical data is consistent with the structure:

Rh (acac) EXAMPLE 9 Bis(diphenylphosphino) ethanepalladium dichloride (16 parts) and bis(phcnyl cyanide) palladium dichloride (22 parts) were dissolved in toluene and left to stand for 46 hours. At the end of this time the product (19 parts) was filtered off, and dried it did not decompose below 300 C.

Elemental analysis.-C, 41.7 (41.5); H, 3.2 (3.2). Analytical data is consistent with the structure:

What I claim is: 1. A process for the preparation of bridged dinuclear transition metal compounds which comprises the reaction of (a) a first transition metal compound having directly bonded to the metal two non-chelating ligands containing electron-donating groups in cis positions relative to each other, the compound also including other ligands as required to satisfy the valence and co-ordination requirements of the metal, said compound (a) being represented by the formula:

with

(b) a second transition metal compound containing a displaceable norbornadiene ligand or two other displaceable ligands in cis position relative to each the reaction causing the displaceable ligands to be displaced from the second transition metal compound so as to form a bridged dinuclear compound represented by the formula:

wherein L is cyclopentadienyl, triphenylphosphine and diphenylphosphinoethane, m is 2, M is the first transition metal, X is sulphur, acetylene or chlorine,

n being When X is acetylene or chlorine and n being 1 and R being phenyl When X is sulphur, L

being ethylene, phenyl cyanide, 2-methoxyethanol or both L' taken together being norbonadiene, M

is the second transition metal, L is carbonyl, acetylacetonate and chlorine and p is 1 or 2, being sufficient to satisfy the requirements of the second metal M.

2. A process according to claim 1 in which the reaction is carried out in a solvent capable of liganding with the second transition metal compound to form displaceable ligands, said solvent being selected from the group consisting of toluene, methylene chloride and 2-methoxyethanol.

3. A process according to claim 1 in which the metal is selected from rhodium, cobalt, nickel, palladium, platinum, molybdenum and titanium.

4. A process according to claim 1 wherein the first transition metal compound (a) is selected from the group consisting of dicyclopentadienyldithiophenyltitanium, bis (triphenylphosphine)cobalt dichloride, bis(triphenylphosphine) nickel dichloride, bis(diphenylphosphino)ethanedithiophenylnickel, and bis(diphenylphosphino)ethanepalladium dichloride, and wherein the second transition metal compound (b) is selected from the group consisting of norbornadienetetracarbonylmolybdenum, bis(ethylene)rhodium acetylacetonate, bis(phenyl cyanide) palladium dischloride, and bis(pheny1 cyanide)platinum dichloride.

References Cited Benson et al.: Chem. Commun. 1968, pp. 1506-7.

Tilney-Bassett: J. Chem. Soc. 1963, pp. 4784-8.

Hayter: J. Am. Chem. Soc., (1963), pp. 3120-4.

Canolin et al.: Reactions of Transition Metal Complexes, Elsevier Publishing Co., Amsterdam, 1968, pp. 398, 400.

JAMES E. POE-R, Primary Examiner A. P. DEMERS, Assistant Examiner US. Cl. X.R.

252-431 P; 260429 J, 429.5, 439 R 

